Scrub the cast iron with warm water and a stiff brush or steel wool
For light rust, use coarse salt and a little oil to scrub the surface
For heavier rust, soak the item in white vinegar for a short time
Check frequently while soaking to avoid damaging the metal
Rinse thoroughly with water after removing rust
Dry immediately and completely with a towel
Heat the cast iron on the stove or in the oven to remove all moisture
Apply a thin layer of cooking oil to the entire surface
Bake the cast iron upside down in the oven to re-season it
Repeat seasoning if needed until the surface is protected
Store in a dry place to prevent rust from returning